From mboxrd@z Thu Jan  1 00:00:00 1970
From: matwey.kornilov@gmail.com (Matwey V. Kornilov)
Date: Fri, 30 Jan 2015 15:43:40 +0300
Subject: spinlock variable protection
Message-ID: <mafu9s$mhn$1@ger.gmane.org>
To: kernelnewbies@lists.kernelnewbies.org
List-Id: kernelnewbies.lists.kernelnewbies.org

Hi,

I have the following code

         int ret = 0;
         unsigned long irqflags;

         spin_lock_irqsave(&lock, irqflags);

         //...
         ret = hdl->count;
         //...

         spin_unlock_irqrestore(&lock, irqflags);
         return ret;

I would like to be sure, that ret will not be optimized out. I think 
compiler can convert the code to equivalent:

         unsigned long irqflags;

         spin_lock_irqsave(&lock, irqflags);

         //...
         //...

         spin_unlock_irqrestore(&lock, irqflags);
         return hdl->count;

But this is not what I want, because I use lock to protect hdl and want 
to return hdl->count value as it was in protected section.